basic-vcs/src/commands/write-tree.cpp

#include "write-tree.h"

#include <iostream>
#include <filesystem>
#include <fstream>
#include <string>
#include <string_view>

#include "sha1.hpp"
#include "zstr.hpp"

struct node
{
    std::string name;
    int mode;
    std::string hash;
};

uint8_t hexToRaw(const char firstDigit, const char secondDigit)
{
    uint8_t result = 0;
    switch (firstDigit)
    {
        case '0': result = 0x0; break;
        case '1': result = 0x1 << 4; break;
        case '2': result = 0x2 << 4; break;
        case '3': result = 0x3 << 4; break;
        case '4': result = 0x4 << 4; break;
        case '5': result = 0x5 << 4; break;
        case '6': result = 0x6 << 4; break;
        case '7': result = 0x7 << 4; break;
        case '8': result = 0x8 << 4; break;
        case '9': result = 0x9 << 4; break;
        case 'a': result = 0xa << 4; break;
        case 'b': result = 0xb << 4; break;
        case 'c': result = 0xc << 4; break;
        case 'd': result = 0xd << 4; break;
        case 'e': result = 0xe << 4; break;
        case 'f': result = 0xf << 4; break;
        default: result = 0; break;
    }

    switch (secondDigit)
    {
        case '0': result |= 0x0; break;
        case '1': result |= 0x1; break;
        case '2': result |= 0x2; break;
        case '3': result |= 0x3; break;
        case '4': result |= 0x4; break;
        case '5': result |= 0x5; break;
        case '6': result |= 0x6; break;
        case '7': result |= 0x7; break;
        case '8': result |= 0x8; break;
        case '9': result |= 0x9; break;
        case 'a': result |= 0xa; break;
        case 'b': result |= 0xb; break;
        case 'c': result |= 0xc; break;
        case 'd': result |= 0xd; break;
        case 'e': result |= 0xe; break;
        case 'f': result |= 0xf; break;
        default: result = 0; break;
    }

    return result;
}

std::string hashDir(const std::string& path)
{

    std::vector<node> nodes;

    for (const auto& object : std::filesystem::directory_iterator(path))
    {
        if (object.is_directory())
        {//recurse into the directory
            nodes.emplace_back(object.path().filename().string(), 40000, hashDir(object.path().string()));
        }
        else
        {
            std::ifstream file(object.path().string());
            std::string fileContent {std::istreambuf_iterator<char>(file), std::istreambuf_iterator<char>()};

            SHA1 checksum;
            checksum.update("blob " + std::to_string(fileContent.size()) + '\0' + fileContent);

            nodes.emplace_back(object.path().filename(), 100644, checksum.final());

            file.close();
        }
    }

    std::sort(nodes.begin(), nodes.end(),
            [](const auto& first, const auto& second){return first.name < second.name;});

    std::string treeObject;

    for (const auto&[name, mode, hash] : nodes)
    {
        treeObject += std::to_string(mode) + " " + name + '\0';
        for (int i = 0; i < 39; i += 2)
        {
            uint8_t byte = hexToRaw(hash.at(i), hash.at(i+1));

            treeObject += static_cast<char>(byte);
        }
    }

    treeObject = "tree " + std::to_string(treeObject.size()) + '\0' + treeObject;

    SHA1 checksum;
    checksum.update(treeObject);
    return checksum.final();
}

int writeTree(const char** argv)
{
    if (!std::filesystem::exists("./.git/objects"))
        std::filesystem::create_directory("./.git/objects");

    std::vector<node> nodes;


    for (const auto& object : std::filesystem::directory_iterator("./"))
    {
        if (object.path().filename() == ".git") continue;

        if (object.is_directory())
        {//recurse into the directory
            nodes.emplace_back(object.path().filename().string(), 40000, hashDir(object.path().string()));
        }
        else
        {
            std::ifstream file(object.path().string());
            std::string fileContent {std::istreambuf_iterator<char>(file), std::istreambuf_iterator<char>()};

            SHA1 checksum;
            checksum.update("blob " + std::to_string(fileContent.size()) + '\0' + fileContent);

            nodes.emplace_back(object.path().filename(), 100644, checksum.final());

            file.close();
        }

    }

    std::sort(nodes.begin(), nodes.end(),
                [](const auto& first, const auto& second){return first.name < second.name;});

    std::string treeObject;

    for (const auto&[name, mode, hash] : nodes)
    {
        treeObject += std::to_string(mode) + " " + name + '\0';
        for (int i = 0; i < 39; i += 2)
        {
            uint8_t byte = hexToRaw(hash.at(i), hash.at(i+1));

            treeObject += static_cast<char>(byte);
        }
    }

    treeObject = "tree " + std::to_string(treeObject.size()) + '\0' + treeObject;

    SHA1 checksum;
    checksum.update(treeObject);

    const std::string hash = checksum.final();
    std::cout << hash << "\n";

    const std::string hashDir = "./.git/objects/" + hash.substr(0,2);

    if (!std::filesystem::exists(hashDir))
    {
        std::filesystem::create_directory(hashDir);
    }

    zstr::ofstream outputFile(hashDir + "/" + hash.substr(2));
    outputFile.write(treeObject.c_str(), treeObject.size());

    outputFile.close();

    return 0;
}